Nowadays and due to the increasing selective collection of paper and cardboard, the problem for the waste papers is becoming important in cities and industrialized areas. Although in the present days a big amount of these waste papers are recycled. Many of these waste papers are returning to the paper or cardboard cycle, but a significant part of theses waste papers include important amounts of additives, inks, glues, wet resistance resin, etc., and makes the recycling process very expensive and in many cases not sustainable from an environmental point of view. This kind of waste or residue must be sent to dump, becoming then a problem for the environment and the economics in a company.
This problem is particularly found in the printing and graphic design companies since they try to avoid generating waste or by-products because of both environmental and economical reasons. In general, there is a trend to reduce the bulk of paper sent to rubbish dump and/or incinerator. Due to these reasons recycling paper and cardboard has been publicly promoted. By recovering and recycling the already used paper the life span of cellulose can be extended and virgin fiber consumption is avoided. Printing and graphic design companies use a different range of papers and inks Some of the by-products or wastes already have a known treatment and their recycling is a part of the normal process in the product life cycle in this industry.
However, there is some paper which is not included in this known recycling treatment. It is high quality paper having a high content of additives. A high quality printing process cannot recover waste paper mainly because of the inks and additives present which makes repulping and recycling a very difficult process. Up to date, all waste produced in the production of this kind of paper must be treated as a waste for a rubbish dump thereby becoming a contaminating source and a significant loss of material and energy, apart from involving a high cost.
Additionally, companies producing high quality printing and writing paper cannot use recycled paper mainly because there is a loss of quality in the final product by the use of pulps in the recycling process.
An approach to solve this problem is by removing additives and inks There are lots of documents disclosing deinking processes (see, for example: US 2009165967; US 2007158039; Separation of ink particles from waste paper by fine-bubbles. El-Shall H., Moudgil B. M., El-Midany A. KONA (2005), 23, 122-128; WO 2005124016 A1; US 2005098278; WO 2004011717; The role of particle size on the deposition efficiency of ink on plastic spheres. AZZAM Mohammed O. J., MOUSA Hasan, AL-MAQRAEI Abduljalil A. Colloids and Surfaces A: Physicochemical and Engineering Aspects (2003), 230(1-3), 207-216; US 2003106654; Coagulation using kerosene for magnetic deinking of waste office paper. Oki Tatsuya, Owada Shuji, Yotsumoto Hiroki, Tanuma Hirokazu, Takeuchi Yuu. Materials Transactions (2003), 44(2), 320-326; WO 2002012618); but most of them use chemical products which can even produce a higher environmental contamination. In some other cases, after removing those additives other products should be added leading to a time-consuming work with a consumption of material and energy and, consequently, becoming a low cost-effective process.
Another example is the document WO 00/15899 which discloses a method for deinking and decolorizing a printed paper, comprising (a) pulping the printed paper to obtain a pulp slurry and (b) diluting the pulp slurry but, where the dye is decolorized with one or more laccasses in the presence of oxygen and optionally one or more chemical mediators.
Recycling Technology
Recycling technology has been proved to be effective for paper from newspapers and cardboard. These products are made of paper containing a low content of fillers and repulping is easy to be carried out. Therefore, for products with a high content of fillers the repulping process is more difficult.
In the currently existing methods for obtaining pulp from used high quality paper, there is always a loss in the resistance of the recovered fiber, a loss in the total fiber yield and a problem in removing additives and inks from the paper. There is also the additional problem of having to add virgin paste to the recovered pulp to obtain an acceptable resistance in the final product. This makes the process and the product more expensive.
Sometimes, mechanical processes such as flotation and flocculation are used for removing non-cellulosic additives of the used paper, such as resins, plastics, polymers, varnishes, coatings, preparations pre- and post-inking or other non-cellulosic products.
In general, additives are removed from the fibers during the defibrillation stage. The used paper is treated in a pulper at alkaline conditions at 50-60° C. in order to achieve a good defibrillation and a pulpable paste. An alternative process is carrying out this operation in cold conditions, thickening the pulp until a consistence higher than 15%, heating it with steam to 60° C. and then introducing a deinker and a bleach agent. The pulp is then left for 2 or 3 hours in a maceration tower with mechanical stirring.
A first problem found with this method is that, in the heating treatment, all substances under melting point remain dispersed in the pulp and cannot be removed any longer, thereby causing subsequent problems in the paper making machine occluding filters, grilles, valves and conductions.
A second problem found is that, these deinking techniques are low efficient for the most modern inks The present inks use resins with a wet resistance as a fixation carrier on the fiber and with these processes, inks cannot be separated from the paper surface and even the adherence to it is not weakened.
A third problem is that the temperature of the deinking process cannot be increased since the extended treatments for a cellulose fiber in alkaline medium at high temperatures makes the pulp get a yellowish color, especially when pieces of wood remains within the paper.
One of the present inventors previously disclosed a process (ES2241408 B1) for recycling waste paper printed on gravure with inks resistant to humidity. However, the mentioned process used a very acidic pH and there is a lot of waste during the process, along with a dramatic reduction of the cellulose fiber length, causing thereby a reduction on the breaking strength in the recycled material. The new process disclosed in the present invention overcomes the mentioned drawbacks and additionally allows to obtain a product with improved properties such as fire-resistant, thermal and acoustic insulation, water-proof characteristics, dimensional stability, low density, high mechanical resistance, hard as wood but capable of being molded, and recyclable.
Therefore, a first object of the present invention is an optimized bioprocess for recycling waste paper originated from high quality paper (printed paper).
A second object of the present invention is the product obtainable from the bioprocess according to the first object.
This “ecological” material has no environmental impact either in its production or in its use. Additionally, it gives added value to the tons of waste paper and cardboard which are accumulated in big cities. The material of the present invention has properties equivalent to the non ecological materials which can then be replaced, with the advantage of being a natural material. In addition, the material production process does not have a negative impact, because it does not generate residues and all the used residues components are recycled in the process itself
As mentioned above, the present product has improved properties such as fire-resistant, thermal and acoustic insulation, water-proof characteristics, dimensional stability, low density, high mechanical resistance, hard as wood but capable of being molded, and recyclable.
A further object of the present invention is the use of the product according to the second object as building and construction material, ecologic packaging material and as eco-decorative material.